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White hot on green

By Stephanie Pain

HIGH-FLYING executives and working mothers, teenagers and little old ladies:
these days everyone’s handling cocaine. In most cases, though, they don’t know
it. They aren’t smoking it and they’re not snorting it: they’re spending it. The
drug is now so widespread that it has contaminated almost every banknote in the
US.

Of course, the amount of cocaine on each note is so small—down in the
nanograms—that you need sophisticated equipment to detect it at all. But
it’s a gift for lawyers defending dealers and pushers. The smart ones argue that
the discovery of cocaine on their clients’ cash proves nothing. And finding
cocaine on their hands is just as meaningless: it could simply have rubbed off
from “ordinary” money.

With such widespread contamination, even the skills of sniffer dogs have been
called into question. In 1994, the 9th US Circuit Court of Appeals ruled that
police officers could not seize suspected drugs money or raid premises just
because a sniffer dog had indicated it was contaminated. They would need better
evidence than that.

Deprived of one of their weapons in the war against drugs, the FBI decided to
track down the source of the problem—and find out whether it really did
invalidate the evidence. “The extent of the contamination surprised everyone
early on,” says Tom Jourdan, a chemist at the FBI’s laboratory in Washington DC.
“How could the bad guys have touched all that money?”

GAMING TABLES

The answer is that they haven’t. Someone who has handled cocaine, then
touched money will transfer several hundred nanograms to a bill, says Jourdan.
But as the …